Competency-Based Question Bank: Evolution

Section A: Competency-Based Multiple Choice Questions (Application & Analysis)

1. Analyze the Scenario: In a population of beetles, the ground color varies from light to dark. Due to volcanic activity, the soil becomes blackened with soot. According to the principle of natural selection, which of the following changes is most likely to occur after 50 generations? a) The beetles will mutate to become green to match the leaves. b) The population will consist mostly of dark-colored beetles. c) The population will be an equal mix of light and dark beetles. d) The beetles will migrate to a new island. Answer: b) The population will consist mostly of dark-colored beetles. Explanation: This is an example of Directional Selection. Dark-colored beetles will be better camouflaged against the soot-covered soil, survive predator attacks, and reproduce more than light-colored beetles.

2. Evaluate the Evidence: Which of the following pairs is an example of Analogy (Convergent Evolution) rather than Homology? a) Forelimb of a Whale and Forelimb of a Bat. b) Thorns of Bougainvillea and Tendrils of Cucurbita. c) Wings of a Butterfly and Wings of a Bat. d) Heart of a Fish and Heart of a Rabbit. Answer: c) Wings of a Butterfly and Wings of a Bat. Explanation: Analogous organs have different structures and origins (Butterfly wing is chitinous; Bat wing is bony/skin) but perform the same function (flight). This indicates different ancestors evolving similar traits.

3. Assertion (A): The introduction of antibiotics led to the appearance of antibiotic-resistant bacteria. Reason (R): Antibiotics caused mutations in the bacteria that made them resistant. a) Both A and R are true and R is the correct explanation of A. b) Both A and R are true but R is not the correct explanation of A. c) A is true but R is false. d) A is false but R is true. Answer: c) A is true but R is false. Explanation: Antibiotics do not cause mutations. Resistant variants already exist in the population due to random mutations. The antibiotic simply acts as a selective agent, killing the susceptible ones and allowing the pre-existing resistant ones to multiply.

4. Predict the Effect: A small group of individuals from a large population migrates to a new, isolated island. After several generations, the allele frequencies on the island are significantly different from the original population. This is an example of: a) Gene Flow b) Bottleneck Effect c) Founder Effect d) Saltation Answer: c) Founder Effect Explanation: The Founder Effect is a type of genetic drift that occurs when a few "founders" start a new population. By chance, their gene pool may not represent the original population.

5. Hardy-Weinberg Application: In a population in Hardy-Weinberg equilibrium, the frequency of the recessive allele 'q' is 0.4. What is the frequency of the heterozygous genotype (2pq)? a) 0.16 b) 0.36 c) 0.48 d) 0.60 Answer: c) 0.48 Explanation: If $q = 0.4$, then $p = 1 - 0.4 = 0.6$. The frequency of heterozygotes is $2pq = 2 \times 0.6 \times 0.4 = 0.48$.

6. Interpret the Graph: If natural selection eliminates individuals with extreme values of a trait (e.g., very high or very low birth weight) and favors the mean value, the selection curve is: a) Directional b) Disruptive c) Stabilizing d) Random Answer: c) Stabilizing Explanation: Stabilizing selection favors the intermediate phenotypes and acts against both extremes, leading to a narrower curve around the average.

7. Identify the Mechanism: The evolution of placental mammals in Australia and North America showing similar forms (e.g., Wolf and Tasmanian Wolf) is an example of: a) Adaptive Radiation b) Convergent Evolution c) Genetic Drift d) Co-evolution Answer: b) Convergent Evolution Explanation: When two unrelated lineages (Placentals and Marsupials) evolve similar adaptations due to living in similar environments/niches, it is called Convergent Evolution.

8. Sequence the events: Arrange the following human ancestors in the correct chronological order of appearance: i. Homo habilis ii. Australopithecus iii. Homo erectus iv. Ramapithecus a) iv -> ii -> i -> iii b) ii -> iv -> iii -> i c) iv -> ii -> iii -> i d) ii -> i -> iv -> iii Answer: a) iv -> ii -> i -> iii Explanation: Order: Ramapithecus (~15mya) -> Australopithecus (~2mya) -> Homo habilis (first tool maker) -> Homo erectus (used fire).

9. Reasoning: Why are "living fossils" like the Coelacanth important in the study of evolution? a) They prove that evolution has stopped. b) They represent a link between two distinct groups (e.g., fish and amphibians). c) They have not changed for millions of years, suggesting stable environments. d) Both b and c. Answer: d) Both b and c. Explanation: Living fossils provide a direct look at ancestral morphologies and help scientists understand major transitions (like from water to land).

10. Analyze the Experiment: In the Miller-Urey experiment, what was the specific purpose of the electric discharge? a) To sterilize the apparatus. b) To simulate volcanic eruptions. c) To simulate lightning as an energy source. d) To separate the gases. Answer: c) To simulate lightning as an energy source. Explanation: Electricity provided the energy needed to trigger chemical reactions between CH4, NH3, and H2 to form organic molecules like amino acids.

11. Assertion (A): Human embryos have gill slits during development. Reason (R): "Ontogeny recapitulates Phylogeny" implies humans evolved from fish-like ancestors. a) Both A and R are true and R is the correct explanation of A. b) Both A and R are true but R is not the correct explanation of A. c) A is true but R is false. d) A is false but R is true. Answer: a) Both A and R are true and R is the correct explanation of A. Explanation: Haeckel's Biogenetic Law states that embryonic development (Ontogeny) repeats the evolutionary history (Phylogeny) of the species.

12. Critical Thinking: If a population is in Hardy-Weinberg equilibrium, which of the following is NOT occurring? a) Random Mating b) No Mutation c) Natural Selection d) Large Population Size Answer: c) Natural Selection Explanation: Natural Selection causes evolution (change in allele frequency). If a population is in equilibrium, it is by definition not evolving, so natural selection is absent.

13. Comparative Anatomy: Which of the following is a vestigial organ in humans? a) Spleen b) Vermiform Appendix c) Pancreas d) Gallbladder Answer: b) Vermiform Appendix Explanation: Vestigial organs are structures that have lost their original function through evolution. The human appendix is a remnant of a larger cecum used by herbivorous ancestors.

14. Application: The indiscriminate use of DDT led to DDT-resistant mosquitoes. This phenomenon is best explained by: a) Lamarckism (Acquired characters). b) Darwinism (Natural selection of pre-existing variants). c) Mutation Theory (Sudden mutation caused by DDT). d) Panspermia. Answer: b) Darwinism (Natural selection of pre-existing variants). Explanation: Pre-existing resistant variants had a survival advantage when DDT was applied. They survived and reproduced, leading to a resistant population.

15. Concept Check: What is the main difference between Darwin's view of evolution and De Vries's view? a) Darwin: Sudden mutations; De Vries: Gradual variations. b) Darwin: Gradual variations; De Vries: Sudden mutations (Saltation). c) Darwin: Use and Disuse; De Vries: Natural Selection. d) There is no difference. Answer: b) Darwin: Gradual variations; De Vries: Sudden mutations (Saltation). Explanation: Darwin believed evolution was a slow, gradual process driven by small variations. De Vries believed it happened in sudden, large jumps (mutations).

Section B: Case-Study & Source-Based Questions

Case Study 1: The Peppered Moth (Biston betularia)

In 1850s England, tree trunks were covered in white lichens. White moths were abundant. By 1920, trees became dark due to soot. Dark moths became dominant.

16. Analyze: What was the selective agent in this scenario? a) The smoke b) The predators (birds) c) The lichens d) The soot Answer: b) The predators (birds) Explanation: Birds are the selective pressure. They ate the moths that were easily visible against the background.

17. Evaluate: Why did the white moth population decline? a) They migrated. b) They were easily spotted by predators against the dark background. c) The soot was toxic. d) They could not find mates. Answer: b) They were easily spotted by predators against the dark background. Explanation: On dark trees, the white moths stood out, while the dark ones were hidden. This is Industrial Melanism.

18. Predict: If pollution controls are implemented and lichens return, what trend would you expect? a) Dark moths remain dominant. b) White moths will increase in number again. c) Both will go extinct. d) A new grey species will evolve. Answer: b) White moths will increase in number again. Explanation: Natural selection will favor the white variant again once the background matches their color.

Case Study 2: Darwin's Finches

Darwin observed finches on Galapagos Islands. They evolved from a common seed-eating ancestor from the mainland into multiple species with different beak shapes.

19. Identify: This phenomenon is called: a) Convergent Evolution b) Adaptive Radiation c) Genetic Drift d) Artificial Selection Answer: b) Adaptive Radiation Explanation: Evolution of diverse species from a common ancestor to occupy different ecological niches in a geography.

20. Reasoning: What was the primary driving force for the change in beak shape? a) Availability of different food sources. b) Geographic isolation. c) Sexual selection. d) Volcanic activity. Answer: a) Availability of different food sources. Explanation: Competition for food forced different groups to specialize (seeds, insects, cactus), leading to different beak adaptations.

21. Context: If a new predator eating only small-beaked finches is introduced, what selection occurs? a) Stabilizing b) Directional (favoring large beaks) c) Disruptive d) No selection Answer: b) Directional (favoring large beaks). Explanation: The mean beak size will shift towards the larger end as small-beaked individuals are removed from the population.

Case Study 3: The Sickle Cell Trait

Heterozygous carriers (HbA/HbS) are resistant to Malaria.

22. Explain: Why has selection not eliminated the harmful HbS allele? a) It hides from selection. b) Because of the "Heterozygote Advantage" against Malaria. c) Mutations happen too fast. d) Genetic Drift. Answer: b) Because of the "Heterozygote Advantage" against Malaria. Explanation: In malaria-prone areas, the benefit of being a carrier (surviving malaria) outweighs the risk of the sickle cell disease, maintaining the allele in the population.

23. Connect: This is an example of: a) Stabilizing Selection b) Directional Selection c) Balancing Selection d) Sexual Selection Answer: c) Balancing Selection (or a type of Stabilizing selection where diversity is maintained). Explanation: It balances the two selective pressures (Malaria vs Anemia) to keep both alleles in the gene pool.

24. Deduce: If Malaria is eradicated, what happens to the HbS allele? a) It increases. b) It will decrease. c) Constant. d) Becomes dominant. Answer: b) It will decrease. Explanation: Without the protection benefit, the negative selection (anemia) will drive the frequency of HbS down.

Section C: Creating, Designing & Critical Thinking

25. Designing a Timeline: Create a timeline of the Origin of Life on Earth. Answer:

4.5 Billion Years Ago (bya): Formation of Earth.
4.0 bya: Formation of water/oceans.
3.5 bya: First Prokaryotic life (Anaerobic).
2.5 bya: Oxygen revolution (Photosynthetic Cyanobacteria).
1.5 bya: First Eukaryotic cells (Endosymbiosis).

26. Formulating a Hypothesis: Scenario: You find upright-walking primate fossils with small brains and stone tools.

Question: Which hominid?
Hypothesis: Formulate a hypothesis about their diet. Answer:
Ancestor: Australopithecus or early Homo habilis.
Hypothesis: Large molars and tools suggest a diet of tough plant material or bone marrow scavenging. The tools allowed them to crack bones for high-energy marrow, which eventually fueled the growth of larger brains in later species.

27. Debating Evolution: Topic: "Is Evolution a 'Theory' or a 'Fact'?" Answer:

Scientific Definition: In science, a Theory is an explanation supported by a vast body of evidence (fossils, DNA, embryology). It is not a "guess."
Fact: The observation that allele frequencies change over time is a Fact. The Mechanism (Natural Selection) is the Theory that explains that fact.

28. Visualizing Natural Selection: Draw three graphs representing Stabilizing, Directional, and Disruptive Selection. Answer: (Visual description)

Stabilizing: Curve becomes narrower and taller in the middle (average).
Directional: The whole curve shifts to the right or left.
Disruptive: The curve dips in the middle and develops two peaks at the ends.

29. Creating a Model: Design a classroom activity for Genetic Drift (Founder Effect). Answer:

Jar: 100 Red and 100 Blue beads (50/50 ratio).
Founding: Close your eyes and pick 5 beads.
Result: If you get 4 Red and 1 Blue, the new population has 80% Red. This random change due to a small starting size represents the Founder Effect.

30. Critical Analysis: "Antibiotics are creating superbugs." Answer:

Correction: Antibiotics do not "create" the resistance. They select for it.
Darwinian View: In any population, rare resistant mutants exist. Antibiotics kill the non-resistant bugs, leaving the resistant ones to survive, multiply, and become the new dominant population.

31. Scenario Planning: A zoo has only 4 tigers left (1 male, 3 females).

Challenge: Evolutionary problems?
Strategy: Propose a breeding plan. Answer:
Problems: Inbreeding Depression (accumulation of harmful recessive traits) and Genetic Drift (loss of diversity).
Strategy: Genetic Rescue. Bring in a male tiger from a different, unrelated zoo or use frozen sperm from a distant population to introduce new alleles (Gene Flow).

Evolution